Greece does that to me too

On the plus side, you’ll be nice and empty when you get to Greece and can stuff yourself with dolmades, spanakopita, gyros, moussaka and baklava. You’re ok talking about food, right?

It seems more like you're getting nauseous from sitting next to strangers for such long periods of time. You could be allergic to other people. Consult your Introvert handbook for details.

There are no 23-hour flights anywhere in the world...?

Sounds like motion sickness; try Bonnie.

You sound like the type of person who tries a new food, then gets a stomach ache later from something completely unrelated, but then proudly tells strangers, for the rest of your life, "but I am allergic to that!"

I assume this is your first flight. You are out here of luck for this flight but I would stop at a pharmacy or call your dr to see if something can be prescribed

you'll be fine, when I was 7 I went on a 16 hour flight to Peru and got really sick midflight. don't let the nausea intimidate you, if it controls you then you will even get more sick.

Looks like United Airlines is trying out new techniques...

I'm not a doctor, but food-poisioning could be a possible culprit here...